/*
 * Copyright 2002-2020 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.transaction.annotation;

import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Role;
import org.springframework.transaction.config.TransactionManagementConfigUtils;
import org.springframework.transaction.interceptor.BeanFactoryTransactionAttributeSourceAdvisor;
import org.springframework.transaction.interceptor.TransactionAttributeSource;
import org.springframework.transaction.interceptor.TransactionInterceptor;

/**
 * {@code @Configuration} class that registers the Spring infrastructure beans
 * necessary to enable proxy-based connection-driven transaction management.
 *
 * @author Chris Beams
 * @since 3.1
 * @see EnableTransactionManagement
 * @see TransactionManagementConfigurationSelector
 */
@Configuration
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
public class ProxyTransactionManagementConfiguration extends AbstractTransactionManagementConfiguration {

	@Bean(name = TransactionManagementConfigUtils.TRANSACTION_ADVISOR_BEAN_NAME)
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	public BeanFactoryTransactionAttributeSourceAdvisor transactionAdvisor() {
		BeanFactoryTransactionAttributeSourceAdvisor advisor = new BeanFactoryTransactionAttributeSourceAdvisor();

		// BeanFactoryTransactionAttributeSourceAdvisor内部定义了一个Pointcut，Pointcut在匹配时会用到transactionAttributeSource来解析类或方法上是否存在@Transactional
		// 理解setTransactionAttributeSource这个属性,就要看advisor对象内部这个参数是干嘛的.
		// 最终解析的时候肯定会调用内部的getPointcut方法来获取信息
		advisor.setTransactionAttributeSource(transactionAttributeSource());

		// 设置切入点
		// 该切入点作用：解析方法或类上是否有@Transactional注解，如果有就执行代理对象的invoke方法，完成方法调用（与aop那一套逻辑相同）
		// 这里的advice对象是TransactionInterceptor
		advisor.setAdvice(transactionInterceptor());
		if (this.enableTx != null) {
			advisor.setOrder(this.enableTx.<Integer>getNumber("order"));
		}
		return advisor;
	}


	// 当上面在调用findTransactionAttribute方法的时候，会调用下面的这个Bean中的方法，即下面的Bean与解析@Transactional注解有关系
	@Bean
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	public TransactionAttributeSource transactionAttributeSource() {
		// AnnotationTransactionAttributeSource中构造了一个SpringTransactionAnnotationParser，用来解析类或方法上的@Transactional注解
		return new AnnotationTransactionAttributeSource();
	}

	@Bean
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	public TransactionInterceptor transactionInterceptor() {
		// 创建对应的advice代理对象TransactionInterceptor类
		TransactionInterceptor interceptor = new TransactionInterceptor();
		// 判断并解析对应的注解信息
		interceptor.setTransactionAttributeSource(transactionAttributeSource());
		if (this.txManager != null) {
			interceptor.setTransactionManager(this.txManager);
		}
		return interceptor;
	}

}
